Trailer wheels
5 lug trailer wheels can be used on cars or pickups without any problem as long as they are DOT stamped. Tandem axle trailer wheels get a lot of side stress when making tight turns, you can see the tires really leaning on the wheels. The DOT stamp is what you need to look for. I have used the 5 lug wheels on Ford pickups over the years with no problems at all.
I have used Ford pickup wheels on trailers before and had them break under heavy loads. The wheels will generally split through the bead when really overloaded on a trailer.
That being said, I have run across wheels for those trailers that don't use studs, they use the bolts with the taper cut on them. Some of them use a different taper angle. These are dangerous to use if the wrong lug nuts are used, as they can loosen.
I would not use the little 12 inch wheels on a vehicle, they are usually only rated for 500 pounds or so.